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Northstar Toolkit is the nonprofit data platform — every US nonprofit and foundation from IRS 990 filings, as free search, a developer API, and an MCP server for AI agents. The 990 base layer is free, and stays free.
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    MCP

    The same API, shaped for agents.

    The MCP server is a thin wrapper over the /v1 API: one tool per endpoint, the same auth and limits. Anything you can do with the API, an agent can do through MCP — look up organizations, pull filings, compare compensation, search semantically.

    Connect

    https://www.northstartoolkit.com
/api/mcp

    Works keyless. Step-by-step setup for Claude.ai, Claude Desktop, Claude Code, Cursor, and ChatGPT is on the Connect page.

    Design notes for agent builders

    • Tools return the API's flat JSON — no prose wrapping, so models can chain calls reliably.
    • Rate-limit errors (429) name the tier and the upgrade path in the message body, so agents can surface the fix verbatim.
    • Every filing-derived record carries tax_year, form_type, and a source block — cite them; the IRS publishes filings with a lag.